1. Technical Field
Embodiments relate generally to communications systems and, more specifically, to demodulation circuits having interference cancellation and improved signal-to-noise ratio performance.
2. Description of the Related Art
In both narrowband and wideband communications systems interference cancellation is the process of removing or “cancelling” the degrading effects of a high power interfering signal that is spectrally adjacent to the input signal of interest (i.e., the desired input signal). This degradation is measured in terms of a reduced bit error rate (BER), reduced distance over which input signals may be communicated over the corresponding communications channel, and increased guard band protection resulting in lower efficiency utilization of the frequency or band of interest, as will be appreciated by those skilled in the art. The use of interference cancellation is prevalent in wideband systems such as cellular telephone systems, terrestrial wireless systems employing IEEE802.16 protocols, and in systems where a wideband, high power transmitter is co-located with a receiver bank, as will also be appreciated by those skilled in the art. In many situations the type or characteristics of the interference is known, or in other situations the interference cancellation system attempts to adaptively characterize or “learn” the type of interference prior to implementing approaches to remove or cancel this interference. There is a need for improved methods, circuits, and systems for interference cancellation in communications systems.